1. Field of the Invention
This invention relates in general to remote control apparatuses and particularly to a remote control apparatus which has input/output terminals in the control sections of a plurality of units which are connected in series so as to allow bidirectional control between any two of the plural apparatuses.
2. Description of the Prior Art
Remote control apparatus are well known which are capable of bidirectional control among different apparatuses such as tuners, tape recorders, amplifiers and other equipment.
In such previously proposed remote control apparatuses, a digital control signal for remote control which is produced by a microprocessor is applied to a common input/output terminal and transmitted through an interface circuit to the data bus line of the microprocessor, or the digital control signal is latched to the common input/output terminal from the data bus line. The interface circuit of these prior art devices includes a latch circuit formed of a D-flip-flop circuit and a buffer circuit formed of N-channel MOSFET (metal oxide semiconductor field effect transistor). It is possible that the buffer circuit will becone equivalent to a diode when the power supply of the apparatus is turned off or when the signal at the input/output terminal is grounded. When, for example, the power source of a tape recorder is turned off the remote control operation between the tuner and the amplifier becomes inoperative and impossible.